1. Field of the Invention
This invention relates to a small-hole electrical discharge machining device and a multiple diesinking-and-small-hole electrical discharge machining device, and a method of multiple diesinking-and-small-hole electrical discharge machining by using the same device.
2. Description of the Related Art
There is a demand for electrical discharging machining on a various face of a work to be machined in a work tank which is filled with a working fluid comprising oil and water. In such case, heretofore, a small-hole electrical discharge machining device having a work tank which can be freely tilted by a turntable, in other words the work can be appropriately tilted in the work tank filled with the above-described working fluid (for example, the Japanese Patent Application Publication No. 2002-307248 as a related art).
In the above-described small-hole electrical discharge machining device, when electrical discharge machining is performed at respective positions at different depths from the level of the working fluid while the turntable is tilted, a position of a gate (overflow gate) which discharges the working fluid appropriately is required to be adjusted by hand so that the height of the working fluid is set at a little upper position from a work section according to a height of the working position (a depth from the level of the working fluid) because a Z-axis servo or an electrode guide goes under the working fluid when the working position is at a deeper depth than that of the fluid level. Accordingly, it is difficult to execute automatic continuous operation for electrical discharge machining.
There has also been another method of adjusting the height of the working fluid by using an over flow gate which is provided in a work tank, and which moves upwardly and downwardly in the work tank powered by a servo motor. However, even in this method, it is difficult to prepare programs when a work has a complex shape. Here, the height of the working fluid means a depth from the bottom of the work tank to the level of the working fluid.
Moreover, according to a conventional method of electrical discharge machining for manufacturing a complex-shaped work as shown in FIGS. 1A through 3B, in which diesinking sections 100A 200A, and 300A are formed in, and through holes (small holes) 100B, 200B, and 300B are further formed in the diesinking sections 100A 200A, and 300A, the method comprises: first electrical discharge machining step for performing a diesinking by using an electrode which has been formed into a predetermined diesinking section's shape beforehand. After this step, the electrode is change to a rod-like or pipe-like electrode, and a relative distance between the level of the working fluid and a surface to be machined is adjusted, and thereafter second electrical discharge machining step for forming the through holes 100B, 200B, and 300B is executed. In other words, another step in which the level of the working is adjusted, other than the step for electrical discharge machining, is required. Accordingly, there has been a problem that the total machining time becomes longer and the machining cost is increased.
Moreover, the above-described diesinking has been executed in a working fluid comprising, generally, oil (mineral oil), because the electrode is remarkably consumed. Accordingly, there has also been a problem that the machining time is further increased.
The present invention has been made in order to solve the above-described problems, the object of the invention is to provide a small-hole electrical discharge machining device comprising a mechanism which automatically controls the height of the working fluid corresponding to a height (coordinate values for the W axis) of the working position of a work, a multiple diesinking and small-hole electrical discharge machining device, and a multiple diesinking and small-hole electrical discharge machining method using the same device.